Product Specification
Green Mode PFC/Flyback-PWM Controller
SG6903
The
patented
interleave-switching
feature
synchronizes the PFC and PWM stages and reduces
switching noise. At light loads, the switching frequency is
continuously decreased to reduce power consumption. If
output loading is further reduced, the PFC stage is turned
off to further reduce power consumption.
For PFC stage, the proprietary multi-vector control
scheme provides a fast transient response in a
low-bandwidth PFC loop, in which the overshoot and
undershoot of the PFC voltage are clamped. If the
feedback loop is broken, the SG6903 will shut off PFC to
prevent extra-high voltage on output. Programmable
two-level output voltage control will reduce the PFC
output voltage at low line input to increase the efficiency
of the power supply.
For the flyback PWM, the synchronized slope
compensation ensures the stability of the current loop
under continuous-conduction-mode operation. Built-in
line-voltage
compensation
maintains
constant
output-power limit. Hiccup operation during output
overloading is also guaranteed.
In addition, SG6903 provides complete protection
functions such as brownout protection and RI pin
open/short.
FEATURES OVERVIEW
Interleaved PFC/PWM switching
Green-mode PFC and PWM operation
No switching of PFC at light loads for best power
saving
Low start-up and operating current
Innovative switching-charge multiplier-divider
Multi-vector control for improved PFC output
transient response
Average-current-mode Control for PFC
Programmable two-level PFC output voltage
PFC over-voltage and under-voltage protections
PFC and PWM feedback open-loop protection
Cycle-by-cycle current limiting for PFC/PWM
Slope compensation for PWM
Constant power limit for PWM
Brownout protection
APPLICATIONS
Switching Power Suppliers with Active PFC
High-Power Adaptors
DESCRIPTION
The highly integrated SG6903 is specially designed
for power supplies consist of boost PFC and flyback
PWM. It requires very few external components to
achieve green-mode operation and versatile protections. It
is available in 16-pin SOP packages.
TYPICAL APPLICATION
© System General Corp.
Version 1.0.1 (IAO33.0061.B0)
-1-
www.sg.com.tw • www.fairchildsemi.com
September 28, 2007
Product Specification
Green Mode PFC/Flyback-PWM Controller
SG6903
PIN CONFIGURATION
VRMS
RI
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
IAC
VEA
FBPFC
RANGE
VDD
OPFC
GND
OPWM
MARKING DIAGRAMS
SG6903 TP
XXXXXXXXYWWV
T:
S = SOP
P :
Z =Lead Free
Null=regular package
XXXXXXXX:
Wafer Lot
Y:
Year;
WW:
Week
V:
Assembly Location
IEA
IPFC
IMP
ISENSE
FBPWM
IPWM
ORDERING INFORMATION
Part Number
SG6903SZ
Pb-Free
Package
16-pin SOP
© System General Corp.
Version 1.0.1 (IAO33.0061.B0)
-2-
www.sg.com.tw • www.fairchildsemi.com
September 28, 2007
Product Specification
Green Mode PFC/Flyback-PWM Controller
SG6903
PIN DESCRIPTIONS
Name
VRMS
Pin No.
1
Type
Line-Voltage
Detection
Function
Line voltage detection. The pin is used for PFC multiplier, RANGE control of PFC output
voltage, brownout protection. For brownout protection, the controller will be disabled after
a delay time when the VRMS voltage drops below a threshold.
Reference setting. One resistor connected between RI and ground determines the
switching frequency. The switching frequency is equal to [1560 / RI] KHz, where RI is in
KΩ. For example, if RI is equal to 24KΩ, then the switching frequency will be 65 KHz.
This is the output of the PFC current amplifier. The signal from this pin will be compared
with an internal saw-tooth and hence determine the pulse width for PFC gate drive.
RI
2
Oscillator Setting
Output for PFC
Current Amplifier
IEA
IPFC
3
4
Inverting Input for
The inverting input of the PFC current amplifier. Proper external compensation circuits will
PFC Current Amplifier result in excellent input power factor via average-current-mode control.
The non-inverting input of the PFC current amplifier and also the output of multiplier.
Non-inverting Input for
Proper external compensation circuits will result in excellent input power factor via
PFC Current Amplifier
average-current-mode control.
Peak Current Limit
Setting for PFC
The peak current setting for PFC.
IMP
5
ISENSE
6
FBPWM
7
The control input for voltage-loop feedback of PWM stage. It is internally pulled high
PWM Feedback Input through a 6.5 KΩ resistance. Usually an external opto-coupler from secondary feedback
circuit is connected to this pin.
PWM Current Sense
The current sense input for the Flyback PWM. Via a current sense resistor, this pin
provides the control input for peak-current-mode control and cycle by cycle current
limiting.
The totem-pole output drive for the Flyback PWM MOSFET. This pin is internally clamped
under 17V to protect the MOSFET.
Ground
The totem-pole output drive for the PFC MOSFET. This pin is internally clamped under
17V to protect the MOSFET.
The power supply pin.
Two-level output-voltage setting for PFC. The PFC output voltage at low line can be
reduced to improve efficiency. The RANGE pin has high impedance whenever the VRMS
voltage is lower than a threshold.
The feedback input for PFC voltage loop. The inverting input of PFC error amp. This pin is
connected to the PFC output through a divider network.
IPWM
8
OPWM
GND
OPFC
VDD
RANGE
9
10
11
12
13
PWM Gate Drive
Ground
PFC Gate Drive
Supply
PFC Output-voltage
Control
Voltage Feedback
Input for PFC
FBPFC
14
VEA
15
Error-Amp Output for The error-amp output for PFC voltage feedback loop. A compensation network (usually a
PFC voltage feedback capacitor) is connected between this pin and ground. A large capacitor value will result in
loop
a narrow bandwidth and hence improve the power factor.
Input AC Current
Before start-up, this input is used to provide startup current for VDD. For normal operation,
this input is used to provide current reference for the multiplier.
IAC
16
© System General Corp.
Version 1.0.1 (IAO33.0061.B0)
-3-
www.sg.com.tw • www.fairchildsemi.com
September 28, 2007
Product Specification
Green Mode PFC/Flyback-PWM Controller
SG6903
BLOCK DIAGRAM
© System General Corp.
Version 1.0.1 (IAO33.0061.B0)
-4-
www.sg.com.tw • www.fairchildsemi.com
September 28, 2007
Product Specification
Green Mode PFC/Flyback-PWM Controller
SG6903
ABSOLUTE MAXIMUM RATINGS
Symbol
V
VDD
I
AC
V
High
V
Low
P
D
T
J
T
STG
R
θ
j-C
T
L
V
ESD,HBM
V
ESD,MM
Parameter
DC Supply Voltage*
Input AC Current
OPWM, OPFC, IAC
Others
Power Dissipation At T
A
< 50°C
Operating Junction Temperature
Storage Temperature Range
Thermal resistance (Junction to Case)
Lead Temperature (Wave soldering or IR, 10seconds)
ESD capability, HBM model
ESD capability, Machine model
Value
25
2
-0.3 to +25
-0.3 to +7
0.8
-40 to +125
-55 to +150
41.95
260
4.5
250
Unit
V
mA
V
V
W
℃
℃
℃/W
℃
KV
V
*All voltage values, except differential voltages, are given with respect to GND pin.
*Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device.
RECOMMENDED OPERATING CONDITIONS
Symbol
T
A
Parameter
Operating Ambient Temperature*
Value
-20 to +85
Unit
℃
*For proper operation, electrical characteristics (12V<V
DD
<20V, -20°C <T
A
<85°C Unless noted)
VDD section
Symbol
V
DD-OP
I
DD-ST
I
DD-OP
V
DD-ON
V
DD-OFF
V
DD-OVP
t
D-VDDOVP
V
DD-TH-G
Parameter
Continuously Operating Voltage
Start-up Current
Operating Current
Start Threshold Voltage
Min. Operating Voltage
VDD OVP Threshold
Debounce Time of VDD OVP
VDD Low-Threshold Voltage to Exit
Green-OFF Mode
0V < V
DD
< V
DD-ON
V
DD
= 15V; OPFC, OPWM open; RI
= 24KΩ
15
9
23.5
8
10
6
16
10
24.5
Test Conditions
Min.
Typ.
Max.
20
25
10
17
11
25.5
25
Unit
V
µA
mA
V
V
V
µs
V
DD-OFF
V
DD-OFF
V
DD-OFF
V
+1.5
+2.1
+0.9
© System General Corp.
Version 1.0.1 (IAO33.0061.B0)
-5-
www.sg.com.tw • www.fairchildsemi.com
September 28, 2007
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